The effects of nutrition on reproduction in the Eastern Rainbowfish, Melanotaenia splendida splendida

Badger, Amanda Catherine (2004) The effects of nutrition on reproduction in the Eastern Rainbowfish, Melanotaenia splendida splendida. Masters (Research) thesis, James Cook University.

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Fish broodstock raised in an aquaculture setting must be provided with a diet not only adequate to meet the demands of their basic metabolic functions, but also to support reproduction. The frequency, ration, and types of nutrients provided within a diet are all very important to the performance of broodstock. The eastern rainbowfish, Melanotaenia splendida splendida, can be easily reared and readily spawn in captivity. This species has many characteristics that make it a good model species for reproductive experiments and is also commercially important to the aquarium trade. Studies were carried out to investigate the effects of nutrition on reproductive performance of this species. Firstly, experiments were carried out to establish the basic reproductive parameters of M. splendida splendida. Periods of starvation were then carried out to gauge which parameters would be the more effective indicators for reproductive performance of the fish broodstock. It was determined that egg number, survival to eyed embryo, hatching rate, and unfed larval life were the parameters that would indicate reproductive success of this fish. The next two studies were carried out to evaluate feeding frequency and feeding ration on reproductive performance in this species. Different feeding regimes were designed with feeding frequencies at every one, two, three, four and five days and feeding rations of 100%, 50%, 25%, and 12.5% satiation. The results showed that the reproductive parameters significantly declined when fish were fed less then every day, and less then 100% satiation. The effects of energy, protein and lipid content on reproduction were then assessed. Diets containing 17 MJ Kg-1, 14 MJ Kg-1 and 11MJ Kg-1 were made and tested. The 17 MJ KG-1 energy diet resulted in the highest egg number as well as the longest unfed larval life. The protein experiment examined the effects of three protein levels, 35%, 43% and 50%, on reproductive parameters. The results showed that the 35% protein level gave reduced reproductive success (p<0.05). The 43% and 50% level diets gave better reproductive success but between the treatments had no significant differences in reproductive parameters (p>0.05). The 43% protein diet was recommended for subsequent experiments as it resulted in the longest unfed larval life and it would theoretically cost less to provide and would likely reduce water quality problems. Three diets containing 20%, 12% and 9% lipid were evaluated. The 20% lipid diet caused deformities in larvae, and led to reduced fertilisation and hatching rates. The 12% lipid diet gave the best overall results (p<0.05). Three essential fatty acids, arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), were respectively supplemented into three diets, a fourth diet was supplemented with all three fatty acids and a fifth had no fatty acid supplementation and was used as a control. Egg number, survival to eyed embryo and hatching rate were not significantly different in any of the four diets containing no or only one fatty acid(p>0.05), however, supplementation of the diet with all three fatty acids resulted in significantly longer unfed larval life (p<0.05). In summary, the results of the current study showed that a diet containing 17 MJ KG-1 energy, 43% protein, 12% lipid and supplemented with all three fatty acids at the levels tested would maximise the level of reproduction in M. splendida splendida.

Item ID: 961
Item Type: Thesis (Masters (Research))
Keywords: Eastern rainbowfish, Melanotaenia splendida splendida, Effects of nutrition on reproductive performance, Egg number, Survival to eyed embryo, Hatching rate, Unfed larval life, Feeding regimes, Diet, Arachidonic acid, Eicosapentaenoic acid, Docosahexaenoic acid
Date Deposited: 04 Oct 2006
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0704 Fisheries Sciences > 070401 Aquaculture @ 0%
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